1. Field of the Invention
This invention relates in general to magnetic heads and in particular to magnetic heads of the flux-sensitive type.
2. Description Relative to the Prior Art
The playback of recorded signals from magnetic tape, or the like, using a conventional magnetic head that is sensitive to flux rate-of-change is difficult at low recorded signal frequencies, and theoretically impossible for recorded dc signals, or when there is no relative head-to-tape speed. Various techniques have been proposed for sensing tape flux, as opposed to the rate-of-change of flux (viz. Hall-effect devices; flux gate devices; etc.). The invention, as will be described below, employs a "single domain" thin magnetic film structure, such as a wire plated with permalloy, say, to less than three microns in thickness. (The plating occurs while the wire conducts a current, thereby providing the permalloy film with an easy magnetic axis that is parallel to the circumferential skin of the wire and orthogonal to the length of the wire).
Thin film magnetometers have been described in the literature, and in a number of patents:
Ieee transactions on Magnetics, Vol. MAG8, #1, March 1972, "Magnetic Thin-film Magnetometers for Magnetic-field Measurement"; PA0 U.s. pat. No. 2,856,581, issued in 1958 to L. Aldredge; PA0 U.s. pat. No. 3,012,177, issued in 1961 to H. Mortimer; PA0 U.s. pat. No. 3,239,754, issued in 1966 to W. Odom, Jr.; and PA0 U.s. pat. No. 3,271,665, issued in 1966 to P. Castro.
Despite widespread knowledge of thin magnetic films, no known use of such a film in connection with a magnetic head for the playback of magnetically recorded signals has been indicated, let alone the specific teachings of the invention.